Oversized BMS?

Dedou

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Jan 7, 2022
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Is there an oversized bms problem? I ordered 4pcs 230ah EVE cells (max discharge current 1C) and 200A 4s JBD BMS, currently the consumption is 100-300w, but in the future if I want to use more than 2000w. Is this configuration safe to protect cells?
 

HRTKD

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As I recall, my Overkill Solar (aka JBD) 4s 120 amp BMS has a maximum amp/discharge setting. You may be able to set that on yours. However, it's either on or off. There is no throttling.

Check the data sheet for your cells. Is 1C the continuous discharge?

In my system, I knew I could end up pulling more than 2000 watts, but not more than 3000 watts. I created two separate batteries, each with a 120 amp BMS. I'll probably never hit 240 amps, but if my connections to the two batteries are well balanced, I should be able to hit that if I need it.
 

Dedou

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Thanks for the answer.

Yes, the continuous discharge is 1C.

I know it gets adjusted in the settings, I'm just wondering why buy a smaller bms when this bigger one can be adjusted to the same level. I thought if there was anything wrong with the bigger one vs. smaller.
 

HRTKD

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Thanks for the answer.

Yes, the continuous discharge is 1C.

I know it gets adjusted in the settings, I'm just wondering why buy a smaller bms when this bigger one can be adjusted to the same level. I thought if there was anything wrong with the bigger one vs. smaller.

If I had a single battery then the 200 amp BMS is likely what I would go with. At the time I created my system, the 120 amp BMS is all that was available. It's a Known Good BMS. The larger amp versions are still fairly new and may not have enough time in the field for us to know if they are as reliable as the 120 amp version. JBD has a good reputation so far. I would expect the larger amp versions to work well. But you never know.
 

Dzl

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I have never heard any reason not to go with a bigger BMS than you need, in fact, that is exactly what many people would recommend.

If I were buying a budget 4S BMS today, I think I would go with the new-ish 200A JBD BMS. This BMS wasn't on the market, or at least not on our radar a year or two ago. The choice was either 120A JBD BMS or expensive high current Daly BMS. Now we have more options.
 
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